Safety-conductor for electric lights



, to Model.)

- T. A. EDISON. Safety-Conductor for Electric-Lights.

No; 227,226. Patented May 4,1880.

NJETERS, PHOT0-LITHOGRAPHEFL WASHINGTON. l) .(L

'ular branch, but no more.

UNITED STATES PATENT OFFICE.

THOMAS A. EDISON, OF MENLO PARK, NEWV JERSEY.

SAFETY-CONDUCTOR FOR ELECTRIC LiGHTS.

SPECIFICATION forming part of Letters Patent No. 227,226, dated May 4, 1880.

Application filed March 25,1880.

To all whom, it may concern:

Be it known that l, THOMAS A. EDISON, of Menlo Park, in the county of Middlesex and State of New Jersey, have invented a new and useful Improvement in Conductors for Electric Lights; and I do hereby declare that the following is a full and exact description of the same, reference being had to the accompanying drawings, and'to the letters of reference marked thereon.

In other applications for patents made by me I have shown a safety device for preventin g an abnormal flow of currentthrough any branch. This safety device consists of apiece of very small conductor interposed in the main conductors of a house or in the derived circuit of a lamp. Preferably, one is interposed in the circuit of each lamp or other translating de vice. This small conductor has such a degree of conductivity as to readily allow the passage of the amount of current designed for its partic- If, from any cause whatever, an abnormal amount of current, large enough to injure the translation devices or to cause a waste of energy, is diverted through a branch the small safety-wire becomes heated and melts away, breaking the overloaded branch circuit. It is desirable, however, that the few drops of hot molten metal resulting therefrom should not be allowed to fall upon carpets or furniture, and also that the small safety-conductor should be relieved of all tensile strain 5 hence I inclose the safet -wire in a jacket or shell of non-conducting material, which, preferably, is secured to the ends of the large conductors, uniting them, not electrically, but as to tensile strain.

(No model.)

dinarily used in its particular circuit, but

melting and thereby breaking the circuit when the current is injuriously increased.

In Fig. 3 A is a simple shell placed over the safety-wire only. The preferable form is shown in Fig. 1, where A is a shell composed of two halves, a, one of which is shown in Fig. 2. This shell is made slightly tapering at the ends, and with a slight inward flange, so as to grasp firmly the wire B B.

The two halves are placed so as to form a complete cylinder, the ends grasping the wire B B, and the-hoops or bands E E slipped on.

This arrangement forms a shell or case for the safety-wire, and at the same time relieves it of tensile strain, the strain of the wire B B being carried by the case.

hat I claim is 1. The combination, with the safety wire or device, of an inclosing case or shell, substantially as set forth.

2. The combination, with the safetywire and main severed conductor, of a shell or case inclosin g the safety device or wire and relievin it from strain, substantially as set forth.

This specification signed and witnessed this 10th day of March, 1880.

THOS. A. EDISON.

IVitnesses:

WM. CARMAN, O. P. Mom. 

